The authors agree that Biraghi is a surname of the Milan area, derived from the place name Birago.

E. De Felice describes it as a surname of the Lombardy area, frequent especially in the city of Milan, formed from the place name Birago, which appears twice in the province of Milan: in the municipality of Lentate sul Seveso and in that of Terranuova dei Passerini.

E. Rossoni agrees in noting it as typically of the Lombardy area, concentrated in the city of Milan, and derives it probably from the place name Birago.

F. De Laurentiis repeats De Felice's description and presents it as a surname of the Lombardy area, frequent especially in the city of Milan, formed from the place name Birago, present in the province of Milan in the municipalities of Lentate sul Seveso and Terranuova dei Passerini.

Surnames in Italy goes deeper into the origin of the place name. Birago is considered a predial place name —that is, linked to lands as objects of legal or fiscal norms— with the Gaulish suffix in -acum. In the oldest forms confirmed so far (years 942 and 996), under the spelling Biulaco, the Latin name Bibulus is recognised, which suggests that the place name would correspond to a rus bibulacum, a property of a Roman named Bibulus. The noble family of Birago, present in the territory since before the year 1000, figures in 1377 among the nobles of Milan with the right to the passive election of the ordinary canons of the Duomo.